Heavy fuel oil (HFO) is a category of fuel oils of a tar-like consistency. It is also known as bunker fuel, or residual fuel oil, HFO is the result or remnant from the distillation and cracking process of petroleum.

Heavy fuel oil (HFO) is a category of fuel oils of a tar-like consistency.
It is also known as bunker fuel, or residual fuel oil, HFO is the result or remnant from the distillation and cracking process of petroleum.